The fornix is a C-shaped bundle of fibers (axon

Axon

An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....

s) in the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

, and carries signals from the hippocampus

Hippocampus

The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 to the hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

.

Structure

The fibres begin in the hippocampus on each side of the brain (where they are also known as the fimbria); the separate left and right side are each called the crus of the fornix. The bundles of fibres come together in the midline of the brain, forming the body of the fornix. The inferior edge of the septum pellucidum

Septum pellucidum

The septum pellucidum , and not to be confused with the medial septum, is a thin, triangular, vertical membrane separating the anterior horns of the left and right lateral ventricles of the brain...

 (a membrane that separates the two lateral ventricles) is attached to the upper face of the fornix body.

The body of the fornix travels anteriorly and divides again near the anterior commissure

Anterior commissure

The anterior commissure is a bundle of nerve fibers , connecting the two cerebral hemispheres across the midline, and placed in front of the columns of the fornix...

. The left and right parts reseparate, but there is also an anterior/posterior divergence.

• The posterior fibres (called the postcommissural fornix) of each side continue through the hypothalamus
  Hypothalamus
  The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
  
   to the mammillary bodies; then to the anterior nuclei of thalamus
  Anterior nuclei of thalamus
  The anterior nuclei of thalamus are collection of nuclei at the rostral end of the dorsal thalamus.-Inputs and outputs:...
  
  , which maps to cingulate cortex
  Cingulate cortex
  The cingulate cortex is a part of the brain situated in the medial aspect of the cortex. It includes the cortex of the cingulate gyrus, which lies immediately above the corpus callosum, and the continuation of this in the cingulate sulcus...
  
  .
• The anterior fibers (precommissural fornix) end at the septal nuclei
  Septal nuclei
  The septal area are structures that lie below the rostrum of corpus callosum in front of lamina terminalis , composed of medium-size neurons grouped into medial, lateral, and posterior groups...
  
   and nucleus accumbens
  Nucleus accumbens
  The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...
  
   of each half of the brain.

External links

• Photo at umdnj.edu
• NIF Search - Fornix via the Neuroscience Information Framework
  Neuroscience Information Framework
  The Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/genomic resources.-Description:...
  
  
• More info at BrainInfo